Out of interest, which icon scheme is being used in the screenshots?
Topic on Talk:Style guide/Forms
They are not from a set. They are hand-built for the functions. They're mine entirely with one exception (the trash can icon) which I built from an icon created by Trevor Parscal (I would have used it directly but his version of it has grey lines and a white background and isn't suitable for use on a button, so I recreated it in pure white).
I've added direct assets for the three circular icons (checkmark, alert mark, and no mark) in both png and svg formats. They're at the bottom of the page, under "Assets". I am assuming this is what you were referring to.